Production of acids



Patented Apr.- 8, 1930 i v UNITED STATES PATENT OFFICE HERMANN FRISGHER, F COLOGNE-LINDENTHAL, GERMANY rnonuorron or ACIDS No Drawing; Application filed May 16, 1927, Serial No. 191,919, and in Germany May 26, 1926.

My invention refers to the production of view of the homogeneity of the mixture the inorganic acids from the respectivesalts, and operation can be carried out advantageously more especially to the production of acids, in horizontal cylindrical stills heated from such as nitric acid, from nitrates, by acting within or from without, these stills being thereon with a stronger acid, for instance either provided with agitating devices 'or sulfuric acid. It is an object of my invention being revoluble. The use of such cylinders to provide means whereby the reaction beas compared with the stills hitherto used intween the stronger acidand the salts of the volves the double advantage that the material weaker acid is promoted to such an extent acted upon is kept in contact with the entire that less of the stronger acid and lower temh ing surface, while in an ordinary still 55 peratures are required than according to the h is conveyed m inly to the ottom layer practice hitherto followed, of the charge. Ifnon-homogeneous mixtures As is well known to those skilled in the art, are operated upon in horizontal cylindrical acids such as nitric acid are produced by restills, there is a danger that the liquid phase acting on nitrates with sulfuric acid, the sep at s I m the S lid phase. quantity of sulfuric acid required exceeding W acting I' 'Q B o Prod ce nitric the molecular quantity, M ti l r-1 if acid, the invention offers the further advanacting on nitrates for the production of nitric tage that instead of the acid bisulfate hitheracid, a comparatively large Surplus of 5111- to obtained an almost neutral sulfate is obfuric acid must be employed, provided that ll nch commands a higher price.

a high yield of nitric acid shall be obtained. Moreover; while acc rdi g to t eold meth- In the present day practice the quantity of when c i g 011 nitrates for the P dIIC- sulfuric acid employed is such that an acid @1011 of technlcauy neutral sulfates: high sodium sulfate is formed, as a rule a so-called Peratures g g between 600 o 900 C- teehni albi lf t Were-required, my novel method can be car- 70 N d 100 k di nitrate require ried out at temperatures ranging between about 93 kgs. of a 98 per cent sulfuric acid. 0- and 3500 I h now f d h in all cases b t I have further found that the reaction beti ll l h molecular quantigy f lf i tween the salts and the acids can be materialacid will be required, provided that the salts y accelerated y Operating under reduced t b t d upon i fi l ground diti pressure. Thus, if the operation is carried are mixed not only with sulfuric acid, but through at a Pressure of 500 to of l ith a ll tit f th id hi h mercury below normal, the time for complete hall b bt i d th f i th case f a reaction is reduced to about two thirds. Furi t -with it i id B thus, proceeding thermore the operation at reduced pressure the quantity of 93 kgs. sulf ri id i d also. involves a reduction in temperature.

for producing nitric acid fro 100 kgs, di- Thus, for instance, the reaction between soum nltrateis reduced to about kgs. An addium nitrate and sulfuric acid, which took dit on of about 5 to 10 per cent of the acids placeihitherto at 300 to 350 0., will now 0c to be produced to the respective salt has been our already between 200 and 240 C.

found sufficient for this purpose. If uch The acids can be admixed to the salts either quant ty of the acld to be produced is added without or within thereaction vessels. When to the salt together with the sulfuric acid, a admixing the acids to the salts outside of the fluid homogeneous mixture-is formed, which .stills, I prefer proceeding in such manner that allows operatlng in a continuous manner, In I first only part of the salt tobe operated upon 0 is mixed with some of the acid which shall be produced, the balance of the salt and the reacting acid, such as sulfuric acid, being added'to the mixture.

If proceedin in this manner considerably smaller quantities of the acid to be produced will be required. For instance, if 2000 kgs. sodium nitrate shall be acted upon with sulfuric acid, it sufiices to mix only about kgs. of the salt with about 25 kgs. nitric acid, the balance of nitrate and the sulfuric acid being admixed to'the mixture simultaneously. As

shown by this example even as little as about 1 1.25 per cent nitric acid will suflice as an addition to the reacting mixture. In consequence thereof 'less steam is consumed and the time required for the operation is shortened.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

I claim J r 1. In the process of producing an inorganic acid by acting on one of its salts with another acid to producea neutral salt of said other acid, the step of embodying in the mixture of the starting products a small quantity of acid of the kind which shall be produced.

2. In the process of producing an inor-' ganic acid by acting on one of its salts with another acid to produce a neutral salt of said other acid, the step of embodying in the salt to be acted u on a small quanity of acid of the kind whic shall be produced.

3. In the rocess of-producing an inorganic acid by acting on one of itssalts with another acid-to produce a neutral saltflof said other acid, the step of embodying in. a portion of t salt to be acted upon a small quangity 3f acid of the kind which shall be pro uce 4. In the processi: nitric acid I by acting on a nitrate with sulfuric acid, the

step of embodying in the mixture of the starting products a small quantity of nitric acid.

5. In the process of producing nitric acid by acting on a nitrate with sulfuric acid, the stegeof embodying in a portion of the nitrate to d acted upona small quantity of nitric aci 6. The process of producin an inorganic acid comprising causing anot er acid to act at a pressure below normal on a mixture'of a salt of the acid to be produced with a small quantity of acid of the kind to be produced.

-7. The process of roducing an inorganic acid other than sulfuric acid comprising causing sulfuric acid to act at a pressure below normal on a mixture of a salt of the acid to be produced with a small quantity ofacid of mercury column on a mixture of sodium nitrate and some nitric acid at a temperature 

